The present invention relates to bulldozers or the like having transversely extending material moving blades, and more particularly to an improved and simplified mechanism for angling, tilting, and pitching the material moving blade.
It is known to provide in bulldozers or similar types of earth working machines a pusher frame of C-shaped configuration which fits between the track frames or surrounds the front end of the tractor. The rear ends of the two arms of the C-shaped frame are pivotally connected to the sides of the tractor to permit raising and lowering of the C-shaped frame about a transverse axis thereby permitting lowering of the blade to a working position on the ground and raising of the blade for transport of the dozer tractor to another location.
In non-angling types of known bulldozer blade arrangements, tilting of the blade has been accomplished conventionally by pivotally connecting the back of the blade to the forward end of the push arms of a C-shaped frame and providing extensible and retractable braces or links between each push arm and the top of the blade. Tilting of the blade in this known construction is accomplished by retracting the brace or link on one push arm and at the same time extending the brace or link on the other push arm. This provision, however, requires the use of three pivots between the blade, push arms and the adjustable brace or link just back of the blade.
In known angling types of bulldozer blades, tilting of the blade has been accomplished by employing a double swivel joint between the blade and the central portion of the C-shaped frame that will permit tilting about a fore and aft axis as well as angling about the vertical axis, and by providing a sliding connection between the forward end of each adjustable brace or link in the back of the blade along a circular track in a vertical plane. This known construction makes it difficult to mount the blade compactly and securely on the C-shaped frame and requires tilting adjustment at both ends of the blade.
Conventionally, the load handling blade is mounted on the earth moving equipment by means of a central swivel joint, one part of which is attached to the rear of the blade and the companion part is attached to the pusher frame of the earth moving equipment so as to permit up and down movement, pivotal side or angular movement, and edgewise tilting movement of the blade. Various problems occur in the design of such mechanism, particularly when in addition to the angling provision of the blade, tilting of the blade about a longitudinal axis is desired.
One type of prior art construction provides a pair of fluid cylinders attached to the rear of the blade at one end thereof and having their other end attached to the frame of the earth moving equipment, which, when selectively actuated, vary the pitch angle of the blade by pivoting the blade around a vertical axis of the joint relative to the longitudinal axis of the vehicle. Normally, to vary the vertical position of the blade edgewise for tilting, a separate fluid motor has been provided in addition to the fluid motors for angling of the blade.
With this prior arrangement, when the tilting jack is actuated to accomplish vertical tilt adjustment of the blade, the pair of angling jacks are urged to move arcuately in opposite, vertical directions. A problem with the prior art mounting arrangement is that the arrangement is subjected to excessive stresses, and the amount of tilt adjustment of the blade is restricted. It is well-known that earth moving vehicles of this character are subject to considerable shock loads during operation and therefore must be of extremely rugged construction.
When the blade is set at a desired tilt position, such as for forming a ditch or leveling a road, the blade must be capable of maintaining the grade angle selected. With the prior art arrangements of a pair of angling jacks extending substantially horizontally between respective sides of the blade and the C-shaped frame, if the angle of the blade is changed, the tilt must also be readjusted to maintain the same grade angle. This conventional arrangement requires multiple hydraulic control means and multiple fluid power tubing carried by the earth moving vehicle increasing the difficulties in installation of hydraulic power equipment and further increasing the maintenance of the fliud power equipment and complicating the operation of the controls.
Another problem associated with some prior art blade control arrangements is that they have no pitch capability relative to the longitudinal axis of the vehicle. In bulldozers, complete adjustability of the dozer blade renders the vehicle more versatile. These prior constructions have been relatively complex and extremely bulky, and there has been a need for a simplified mechanical construction and controls therefore that permit complete adjustability of the blade.
These disadvantages of present bulldozer constructions have resulted in the blade adjustment construction and controls therefor in the present invention which effectively eliminates the above difficulties of the prior art.